(Roadrunner)Mixing their trademark raging riffola and tribal drumming with everything from krautrock to acoustic elements, Slipknot push their own limitsSlipknot are never too far from trauma. Having long outlived the terrors of nu-metal, the Iowan masked behemoths’ last album, .5: The Gray Chapter, channelled their grief at founding bassist Paul Gray’s fatal overdose. This sixth album’s similarly tortuous gestation included frontman/best-selling author Corey Taylor’s marriage break-up and a bizarre incident where guitarist Mick Thomson was stabbed in the head by his brother. With so much to be furious about, We Are Not Your Kind contains their most brutal music and yet, albeit occasionally, their gentlest too. The 14 songs push their sonic envelope, meaning that their trademark hooligan riffola and tribal drumming co-exist with experimental krautrock and (gulp) acoustic strums. The electro-pulsing My Pain and avant garde, percussive Spiders have a whiff of Depeche Mode about them, while the silky chorus of the otherwise punky metal Nero Forte wouldn’t be out of place in a mainstream pop banger.